On or before December 31, 1973, every city and county shall prepare, adopt and submit to the Secretary of the Resources Agency a local open-space plan for the comprehensive and long-range preservation and conservation of open-space land within its jurisdiction. Every city and county shall by August 31, 1972, prepare, adopt and submit to the Secretary of the Resources Agency, an interim open-space plan, which shall be in effect until December 31, 1973, containing, but not limited to, the following:
(a) The officially adopted goals and policies which will guide the preparation and implementation of the open-space plan; and
(b) A program for orderly completion and adoption of the open-space plan by December 31, 1973, including a description of the methods by which open-space resources will be inventoried and conservation measures determined.